RFR: 8301703: java.base jdk.internal.foreign.abi.BindingSpecializer uses ASM to generate classes

[Chen Liang]

On Thu, 30 Mar 2023 17:11:44 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

> Rewrite BindingSpecializer to use the new class file API.
> 
> Note: There is a big try/catch/finally block generated in the `specialize` method that currently uses labels. I looked at replacing this with a call to `CodeBuilder::trying` but it would require threading the nested code builders through all the `emit*` methods, which currently access the 'global' CodeBuilder instance attached to the BindingSpecializer instance. Since there didn't really seem to be a big benefit to this, I've kept that try/catch/finally block as is, using labels.
> 
> The current implementation could also use `CheckClassAdapter` to do additional verification on the generated bytecode (ahead of the VM's verifier). I'm not sure if the new API has a replacement for that?

src/java.base/share/classes/jdk/internal/foreign/abi/BindingSpecializer.java line 77:

> 75:     private static final int CLASSFILE_VERSION = ClassFileFormatVersion.latest().major();
> 76: 
> 77:     private static final MethodTypeDesc MTD_VOID = MethodTypeDesc.of(CD_void);

Now that there's a `MTD_void` in ConstantDescs, can switch to use that.

src/java.base/share/classes/jdk/internal/foreign/abi/BindingSpecializer.java line 216:

> 214:         if (PERFORM_VERIFICATION) {
> 215:             boolean printResults = false; // only print in case of exception
> 216:             CheckClassAdapter.verify(new ClassReader(bytes), null, printResults, new PrintWriter(System.err));

Classfile API provides verification functionality as well, as seen here:
https://github.com/openjdk/jdk/blob/83cf28f99639d80e62c4031c4c9752460de5f36c/test/jdk/jdk/classfile/ClassHierarchyInfoTest.java#L105

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PR Review Comment: https://git.openjdk.org/jdk/pull/13247#discussion_r1153653198
PR Review Comment: https://git.openjdk.org/jdk/pull/13247#discussion_r1153654815